As conventional positive displacement compressors, in which the volume of a compression chamber is changed by rotation of a drive shaft, a swash plate compressor, a vane compressor, and a scroll compressor have been known. In a swash plate compressor, pistons are reciprocated at a stroke corresponding to the inclination angle of the swash plate. For example, refer to Patent Document 1. In a vane compressor, vanes protrude from and retract into a rotor while sliding along the inner circumferential surface of the housing. For example, refer to Patent Document 2. In a scroll compressor, a movable scroll orbits about a fixed scroll. Refer, for example, to Patent Document 3.
In these types of positive displacement compressors, the compression chamber draws in fluid through a suction port when the volume of the compression chamber is increased and discharges the fluid through a discharge port when the volume is reduced. Such positive displacement compressors can be employed, for example, for vehicle air conditioners.
In addition, Patent Documents 4 and 5 disclose vane compressors that have compression chambers located at radially outer positions and compression chambers located at radially inner positions. Since the radially inner compression chambers can be provided inside a rotor in these vane compressors, the displacement in relation to the entire volume can be increased.